The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In universal serial bus (USB) devices, surges on input lines of the USB devices can cause loss, corruption and/or degradation of information being carried to the USB devices. Further, the surges can cause the USB devices to transition into non-operational states, disconnect or reset states. In many situations, the loss, corruption and/or degradation of information can be highly undesirable, presenting the challenges of maintaining capture of information through the surge conditions and minimizing the situations where the USB devices transition into non-operational states in response to the surge conditions.
In personal health care applications, in particular, it is desirable for utilized USB devices to be tolerant to electrical fast transient (EFT) disturbances of between −1.5 kilovolts and +1.5 kilovolts coupled to USB communication lines interconnecting the USB devices. Due to EFT disturbances on the USB communication lines of the prescribed level, the input of a USB device may experience an electrical transient voltage of more than one volt on the USB device's differential input lines. The EFT disturbances may result in a change in a common mode voltage of the USB communication lines. This electrical transient voltage often is greater than the normal operation common mode voltage range of −50 millivolts to 500 millivolts for the USB device, causing the USB device to malfunction, transition into a reset or disconnected state, and/or experience false input readings.